There isn't a single CQB place in Toronto that will allow a velocity reducer (despite some of those places being semi only).
Swap the spring. Stick a M90 or M100 (Modify make great springs labeled S90, S100) in there to be sure to get under 350 (some M100's in some guns will still be over).
The Galil's aren't too bad to work on. PM me if you need a hand. I should be able to make arrangements with Shinobii to retain whatever warranty he may be offering.